| 滇中易门地区约1.85Ga凝灰岩的厘定及其地质意义 |
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| 引用本文： | 刘军平,曾文涛,徐云飞,孙柏东,胡绍斌,刘桂春,宋冬虎,吕勃烨,王晓峰.滇中易门地区约1.85Ga凝灰岩的厘定及其地质意义[J].地质通报,2018,37(11):2055-2062. |
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| 作者姓名： | 刘军平 曾文涛 徐云飞 孙柏东 胡绍斌 刘桂春 宋冬虎 吕勃烨 王晓峰 |
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| 作者单位： | 云南省地质调查院, 云南 昆明 650216,云南省环境监测院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216;昆明理工大学国土资源工程学院, 云南 昆明 650093,云南省地质调查院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216,云南省地质调查院, 云南 昆明 650216 |
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| 基金项目： | 中国地质调查局项目《云南1∶5万二街、易门、鸣矣河、上浦贝幅区域地质调查》（编号：DD20160017）和《云南区域地质调查片区总结与服务产品开发》（编号：DD20160345-02） |
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| 摘 要： | 在滇中易门-罗茨断裂带以西前人划分的昆阳群美党组中发现了大量的中酸性凝灰岩。采用锆石激光剥蚀法(LAICP-MS)对易门县铜厂一带的英安质凝灰岩、石英晶屑凝灰岩进行了年龄测定,获得锆石U-Pb年龄加权平均值为1842±26Ma(MSWD=7.6,n=29)和1860±25Ma(MSWD=2.5,n=11)。2件样品的锆石Th/U值为0.2～1.0,且均具清晰的振荡环带结构,为岩浆成因锆石。该套凝灰岩产于一套厚度超过1000m的火山-细碎屑岩组合中,其下发育厚约800m的黑色板岩-碳酸盐岩组合,表明滇中易门地区存在厚度超过2000m的古元古界。此年龄值与全球性的Columbia超大陆事件一致,所以,在进行Columbia超大陆重建时需要充分考虑扬子陆块的位置及意义。
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| 关 键 词： | 古元古界 锆石U-Pb年龄 滇中易门地区 Columbia超大陆重建 |
| 收稿时间： | 2018/3/20 0:00:00 |
| 修稿时间： | 2018/6/25 0:00:00 |
The definition and geological significance of tuffs about 1.85Ga in Yimen area,central Yunnan Province |
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| LIU Junping,ZENG Wentao,XU Yunfei,SUN Baidong,HU Shaobin,LIU Guichun,SONG Donghu,L&#; Boye and WANG Xiaofeng.The definition and geological significance of tuffs about 1.85Ga in Yimen area,central Yunnan Province[J].Geologcal Bulletin OF China,2018,37(11):2055-2062. |
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| Authors: | LIU Junping ZENG Wentao XU Yunfei SUN Baidong HU Shaobin LIU Guichun SONG Donghu L&#; Boye and WANG Xiaofeng |
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| Institution: | Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China,Yunnan Provincial Institute of Environmental Monitoring, Kunming 650216, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China;Kunming University of Science and Technology, Kunming 650093, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China,Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China and Yunnan Institute of Geological Survey, Kunming 650216, Yunnan, China |
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| Abstract: | Medium-acid tuff was extensively found in Meidang Formation of Kunyang Group, which was determined by previous researchers in the west of Yimen-Luoci faults belt. Using the zircon laser denudation method (LA-ICP-MS), the authors obtained weighted average ages of 1842±26Ma (MSWD=7.6, n=29) and 1860±25Ma (MSWD=2.5, n=11) from dacitic tuff and quartz crystal tuff in Tongchang area, Yimen County, central Yunnan Province. Th/U ratios of zircon, which was of magmatic origin and with clear vibration band, were obtained from two samples (0.2~1.0). The tuff was found from a volcanic-microclastic rock assembly, which is over 1000m in thickness. There is a black slate-carbonate rock assembly, which is about 800m in thickness, under the volcanic-microclastic rock assembly. It is thus inferred that there is a large area of Paleoproterozoic strata, which are over 2000m in thickness in Yimen area of central Yunnan Province. The ages coincide with Columbia Supercontinent, and hence Yangtze block''s location and significance ought to be taken into account in the reconstruction process of Columbia Supercontinent. |
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| Keywords: | Paleoproterozoic zircon U-Pb age Yimen area of central Yunnan Province reconstruction process of Columbia Supercontinent |
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